Questions tagged [gravitational-lensing]

Questions regarding the bending of light by mass or energy.

11 questions with no upvoted or accepted answers
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Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection

I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection of the right ascension and declination the galaxies relate to the center of ...
8
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84 views

How well conserved is etendue in extreme gravitational lensing scenarios?

This excellent answer to Could dark matter exist in the Universe in the form of sufficiently dense objects? includes the following image and description: Light from the background galaxy circles a ...
5
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0answers
51 views

What's the largest angle that light has been "seen to bend" by gravity? (of one object by a separate object)

Gravitational lensing is everywhere! because it falls off so slowly with $r$: $$\Delta \phi \approx \frac{4GM}{c^2r_0}.$$ That's the first order term. For a nice derivation see Viktor Toth's The ...
5
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0answers
156 views

Can primordial black holes be found orbiting other stars?

A recent study suggests a that a primordial black hole may be orbiting the sun at and that they can be common near other star systems. What measurements and equipment can perhaps find BH's near ...
4
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0answers
62 views

What exactly would the resolution of an exoplanet hypothetically imaged by using the Sun as a gravitational lens be?

This video talks about how by sending a spacecraft to around 600 AU and beyond, we would could use the Sun as a gravitational lens and take clear detailed images of exoplanets light-years away. What ...
3
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53 views

Could we see small objects like animals on an exoplanet using Solar Gravitational Lensing (SGL) if we could use any star or a black hole for lensing?

Theoretically, if a telescope is positioned in a focal point of a supermassive black hole or a star much more massive than the Sun, would there be a limit to how far away an observable planet can be ...
2
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0answers
49 views

Can the lensing effect of Sagittarius A* be used to image the stars diametrically opposite to the sun?

The sun can magnify an image of a source 100 ly away nearly 100 billion times, if the ring is captured from the nearest focal point (550AU). According to Christian Ready of Launch Pad Astronomy, we ...
2
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0answers
52 views

Within a given image of a multiple-image producing gravitational lens, does Fermat's principle apply?

The question Does gravitational lensing provide time evolution information? is excellent! When we see multiple images of the same object because of the phenomenon of gravitational lensing, do all the ...
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0answers
62 views

Questions on dark matter observations in galaxy clusters

For cluster of galaxies we can observe velocity distributions and so we can deduce mass from multiwavelength observations. I suppose total mass of the cluster could be deduced by observing velocities ...
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0answers
131 views

Will galactic filament indefinitely expand while its galaxy clusters indefinitely disperse?

Exciting discoveries of weak gravitational lensing suggest the existence of galactic filaments made of dark matter that are the size of galactic superclusters. My questions involves the future of the ...
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26 views

Does a gravitational lens around a body look 3-dimensional?

Suppose we approach a neutron star or a stellar black hole close enough, is the gravitational lens around it 3-dimensional (like a tunnel) or is it 2-dimensional? It's 3-dimensional as if you entered ...